Young men who have sex with men (YMSM) are severely affected by the current HIV epidemic. While incidence via all other HIV transmission categories has recently remained stable or decreased, male-to-male sexual contact resulting in HIV infection continues to increase, particularly among young men. HIV prevalence is alarmingly high within the YMSM population (previously estimated at 7% for YMSM ages 15 - 22), but no effective interventions to reduce risk behaviors have been developed for MSM under 23. Parents of YMSM have been identified as an underutilized resource for future risk-reduction interventions within this population, but we know virtually nothing about parental influences on sexual behavior among YMSM. Studies of general adolescent samples reveal that parents have a significant influence on the sexual behaviors of their adolescents. Parental monitoring, parent disapproval of teen sex, family connectedness, and parent-child communication are associated with adolescents' sexual behaviors, including condom use, sex frequency, number of sex partners, and sexual debut. Whether these findings generalize to HIV-related sexual risk behaviors of YMSM is unclear. Limited previous evidence suggests that family connectedness may be protective against sexual risk behaviors among YMSM, but the influences of monitoring, disapproval, or communication have not been examined among YMSM. Moreover, the unique parent-adolescent dynamics that occur when a child is gay, including coming out and parent rejection of sexual orientation, could alter the ways in which previously established family factors influence risk among YMSM. Given the importance of family factors in determining HIV-related sexual risk behaviors, the aims of the current study are threefold: 1) to use data from a large national study to determine which well-established family predictors of adolescent sexual risk also predict risk among YMSM and gay or bisexual young men; 2) to identify through qualitative methods the unique family factors that could predict risk within a family environment where a child is gay or bisexual and 3) to test new family-focused models of YMSM sexual risk behaviors that combine both previously established and newly identified family-relevant predictors. The results of the proposed study could significantly improve future HIV prevention interventions targeting YMSM by advancing knowledge of how to most effectively incorporate parents into prevention efforts. These goals aim to be accomplished within the context of a research training plan focused on developing expertise in the areas of HIV prevention science, advanced mixed-method statistical approaches, and family factors and adolescent health. The training plan proposed includes completion of a number of specific courses, close supervision and individualized mentoring, multidisciplinary collaborations with faculty members, scientific writing and presentation experience, and hands-on clinical work with families and HIV positive individuals. PUBLIC HEALTH RELEVANCE: HIV prevalence is alarmingly high among young men who have sex with men (YMSM) and continues to increase, but no effective interventions to reduce risk behaviors have been developed for YMSM under 23. Family factors are associated with adolescents' sexual risk behaviors, including condom use, sex frequency, number of sex partners, and sexual debut, but it is unclear whether these findings generalize to HIV-related sexual risk behaviors of YMSM. Findings from this study will shed light on the ways that family factors influence HIV risk among YMSM and could help to incorporate parents into and improve future risk-reduction efforts with this population. Such improvements may more broadly reduce health care utilization and national costs of treating HIV positive individuals.